This invention relates in general to cattle stalls, e.g., milking parlors, and is more particularly directed to a technique for releasing cows from a diagonal, herringbone, parabone, or parallel type milking parlor. The invention is more particularly concerned with a push bar that lowers behind the cows, and sweeps forward to urge the cows from the cow stalls after the exit gate or front brisket board moves or lifts away to permit the cows to exit the parlor after milking.
A milking parlor generally consists of an array of individual stalls, each being designed to hold a single cow as she is being milked. The cows are walked into the parlor through an entry gate, and then each cow is directed to her respective stall. There an attendant washes her udders, attaches a milking unit, monitors and attends to the milking operation, disconnects the milking unit, and releases the cows so another group of cows can be milked. In parlors of this type, the cows proceed in single file through the entry gate into the parlor. After the cows have been milked and the milking units removed, an exit gate lifts open at the forward or head side, and the cows exit under this to move to an exit lane. This system is employed in various schemes for milking parlors, including herringbone, diagonal, and parallel or side-by-side, and in hybrid systems such as so-called parabone systems. A parallel milking parlor operation is described in my earlier U.S. Pat. Nos. 5,230,299; 5,285,746; and 5,638,768, which are incorporated herein by reference. An example of brisket bar apparatus for aligning cows in both a herringbone and a diagonal parlor, and for releasing them after milking, is described in Reisgies et al. U.S. Pat. No. 4,951,608.
Sequencing gates, which are required in parallel or side-by-side parlors, are omitted in the diagonal parlor. This simplifies installation, and also aids in cow entry, as it creates a wider lane for the cows.
It frequently occurs that a cow will resist leaving the milking parlor after the milking operation. When this happens, the operator has to take some step to push against her hind end to urge her to move forward. This consumes time from the milking operation, and limits the number of cows that can be milked per hour.
Previously, milking parlors have been proposed with a rotary mechanism that swings down behind the cows when the exit gate opens to push them out of the milking parlor stalls. Each of these uses a pair of brisket bar elements that are mounted on an overhead horizontal axis, and rotate 180 degrees. The upper bar swings down to push out the cows, and becomes the brisket rail for the next group of cows. A version of this in connection with a diagonal or herringbone parlor is discussed in Nelson U.S. Pat. No. 5,203,280 and in connection with a parallel parlor in Nelson U.S. Pat. No. 5,615,637.
In each of these rotary exit gate schemes, the bar is at a fixed radius from the pivot axis. This means that the bar can only travel in an arcuate rotary path, so when the bar moves, it tends to drop down against the cow's back unless she has already started to move forward. In the case of the parallel parlor system, the rotary path of the bar has to be positioned forward of the exit gates, and the bar can strike against the shoulder or neck if the cow has not started forward. In addition, because the rotary exit gate system must have a 360 degree sweep, there has to be a considerable allowance for clearance overhead.